Yeah, I'll keep everyone in-character as best I can blah blah blah...

1. (Very AU) After a tragic lab incident leaving four-year-old Dib and three-year-old Gaz orphans, Zim ends up adopting and raising them, weaseling his own ideals into both’s heads under a thick cover of religious fanaticism. PLOT BEGINS.

2. (Pretty AU) After his wife dies of [SOAP OPERA DISEASE!], Membrane quickly finds a replacement for her through a Zim, who just arrived on Earth (whom he actually believes is female, though Zim just thinks he‘s a bit… backwards and just screws up his genders when he talks, and everyone else is positive Zim is male). Thinking Zim is some kind of foreigner, he takes him under his wing for a time to teach him about general things Zim wouldn’t understand and simultaneously try to convert Zim into a religious fanatic like him. Zim, believing all humans are like this, goes with it.

But Membrane suddenly decides to run off, leaving Zim with Gaz and Dib. (I haven’t decided their ages yet, but I think they’ll be somewhere around how old they are on the show) Riding on the children’s confusion and hurt, combined with their general naive-ness, Zim attempts to teach both that everyone is horrible and bad but Zim, and pretty much succeeds. PLOT BEGINS.

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Zim: You're Tak's ship!
Jhonen: You're exposition!
-"Dibship Rising" Invader Zim DVD Commentary